I seem to remember as a young child being told that it is safe to touch a Van de Graff generator (for the hair demonstration), but that if you let go before it is safe you will get a nasty shock. I know a bit more about electricity now, and I’m a little skeptical now. Is it possible to get a shock from letting go of something?
Does the human body rapidly discharge into air or something?
Enough for a change in potential to cause arcing, as we can see. I’m sure you could find relevant experimental studies, or even conduct them on yourself with a proper transformer and voltmeter.